Incorrect scaling for TreeItem font

[ShahzaibIbrahim]

Incorrect scaling for TreeItem font when moving through different zoom levels.

Contributes to #62 and #127

HOW TO TEST

• Run the ControlExample with the following VM Arguments

-Dswt.autoScale=quarter
-Dswt.autoScale.updateOnRuntime=true

• Switch to the tab "Tree"
• Set any font from the side bar window
• Move the window from 100 to 200 zoom level monitor
• See if scales properly

EXPECTED BEHAVIOUR

The list font should be scaled properly

[github-actions]

Test Results

   470 files  ±0     470 suites  ±0   7m 27s ⏱️ -25s
 4 135 tests ±0   4 127 ✅ ±0   8 💤 ±0  0 ❌ ±0 
16 336 runs  ±0  16 244 ✅ ±0  92 💤 ±0  0 ❌ ±0 

Results for commit b7e5f65. ± Comparison against base commit 23f5c83.

♻️ This comment has been updated with latest results.